If someone hits me in the balls I will lay there ass on the floor. Even if its my friend. This one guy sacked me for no reason so I stuck my elbow through his nose, he wasn't happy.
Don't ever hit a guy in the balls. One, it's lame. Two, if you hit him hard enough he could kill you. It's been proven that hitting even the nicest guy in that special place can make him go totally apeshit. Don't do it!